The invention relates to a device for feeding a pulp suspension to a dewatering installation, particularly for a tissue machine.
This type of device, also known as a headbox, has a major influence on paper formation and thus, on paper quality. In the headboxes used to date, the pressure provided practically the only means of controlling the flow rate of the pulp suspension. In two-layer and multi-layer headboxes, however, which provide a means of influencing the quality of the paper surface, it is not possible to run the different flow rates needed to obtain, for example, different qualities of top and bottom layer.
The aim of the invention is thus to improve the field of application for and the means of controlling headboxes.
The invention is thus characterized by one or several one-piece, wedge-shaped, steel lamella tip(s) being provided to separate the individual sectors in a two-layer or multi-layer headbox. In this way it is possible to achieve stable layer separation and thus, a constant setting of the slice gap heights, even at different feed pressures, with the effect that a differential speed can be set between the individual suspension streams.
An advantageous further development of the invention is characterized by the lamella tip(s) being attached under pre-stress by a tie rod to the partition of the feed device. This allows the setting of the slice gap heights to be particularly stable and as a result, precise.
A favorable configuration of the invention is characterized by the spacing of the bottom lip and/or the top lip to the lamella tip being adjustable. In this way, the lamella tip can be securely fixed and made very stable.
An advantageous configuration of the invention is characterized by an eccentric shaft being provided to set the slice gap between a minimum and a maximum height. By setting the height of the slice gap, the flow rate of the suspension stream can easily be adjusted to the needs of the final product. Since an eccentric shaft is used, this guarantees high-precision adjustment of the slice gap.
A favorable further development of the invention is characterized by the top lip being adjustable using an eccentric shaft, where the bottom lip can also be made adjustable with an eccentric shaft either as an alternative or in addition. The facility for setting the top and/or bottom lip, depending on whether the headbox is of two-layer or multi-layer design, permits optimum conditions for regulating the flow rate for the individual layers.
A favorable configuration of the invention is characterized by a partition and lamella tip unit being adjustable by means of an eccentric shaft.
An advantageous configuration of the invention is characterized by the eccentric shaft being supported at several points over the machine width, where these supports can be positioned at regular intervals.
A favorable further development of the invention is characterized by the eccentric shaft being connected to a gear motor. In this way the slice gap and thus, the flow rate of the pulp suspension can also be set or adjusted accordingly while the paper machine is in operation.